| 摘要 |
<p>PROBLEM TO BE SOLVED: To shorten a time up to start of circuit terminating on startup. SOLUTION: Communication channel modules 11 and 12 are respectively provided with circuit terminating parts 111 and 112 to terminate the circuits of communication data on the basis of clocks CK31 and CK32, synchronous clock generating parts 112 and 122 to respectively generate clocks CK1 and CK2 synchronizing with the frame of data signals from ISDN exchanges 61 and 62, and clock selection parts 113 and 123 which respectively receive the clocks CK1 and CK2, select respectively either of them and output it as a clock CK31 or a clock 32 respectively. The clock selection part monitors a synchronous clock of own communication channel module as well as one of the other communication channel module, and selects one that is first detected. Then, when the synchronous clock of the own communication channel module is detected, the clock selection part selects it.</p> |
